Andrographolide prevents bone loss via targeting estrogen‐related receptor‐α‐regulated metabolic adaption of osteoclastogenesis

Abstract

Background and Purpose Metabolic adaptation driven by oestrogen‐related receptor‐α (ERRα/NR3B1) is required to meet the increased energy demand during osteoclast differentiation. Here, we hypothesize that natural product, andrographolide, acts as an ERRα inverse agonist to inhibit osteoclastogenesis. Experimental Approach Virtual docking and site‐directed mutagenesis analysis were employed to study the binding mode of andrographolide to ERRα. Co‐immunoprecipitation, luciferase reporter assay, real‐time polymerase chain reaction (PCR) and immunoblot analyses were performed to identify andrographolide as an ERRα inverse agonist. The pharmacological effects of andrographolide in vivo were assessed in mice models of osteopenia induced by either a high‐fat diet in male or ovariectomy in female mice. Key Results ERRα‐dependent expression of glutaminase, a rate‐limiting enzyme of mitochondrial glutamine anaplerosis, is required for ex vivo bone marrow osteoclast differentiation. Andrographolide inhibited glutaminase expression induced by ERRα and co‐activator peroxisome proliferator‐activated receptor γ co‐activator‐1β (PGC‐1β), leading to reduction in osteoclastogenesis. Andrographolide acted as an inverse agonist of ERRα by disrupting its interaction with co‐activator PGC‐1β. Phenylalanine 232, valine 395 and phenylalanine 399 of ERRα ligand‐binding domain were confirmed to be essential for this effect. In contrast, glutaminase overexpression restored the impairment triggered by andrographolide. Accordingly, andrographolide suppressed osteoclastic bone resorption and attenuated bone loss in vivo. Conclusions and Implications These findings demonstrate that andrographolide acts as an ERRα inverse agonist for perturbation of ERRα/PGC‐1β/glutaminase axis‐driven metabolic adaption during osteoclast differentiation, implying that andrographolide may be a promising natural compound for preventing physiological and pathological bone loss.

Targeting adipocyte ESRRA promotes osteogenesis and vascular formation in adipocyte-rich bone marrow

“…8k, l ). This result is also consistent with ours and other previous reports that pharmacological inhibition of ESRRA directly blocks osteoclastogenesis and bone resorption 43 . Moreover, SPP1 immunofluorescence staining and plasma P1NP level revealed more osteoblasts and bone formation in C29-treated than vehicle DIO mice (Fig.…”

Targeting adipocyte ESRRA promotes osteogenesis and vascular formation in adipocyte-rich bone marrow

“…8K, L). This result is also consistent with ours and other previous reports that pharmacological inhibition of ESRRA directly blocks osteoclastogenesis and bone resorption 42,43 . Moreover, SPP1 immunofluorescence staining and plasma P1NP level revealed more osteoblasts and bone formation in C29-treated than vehicle DIO mice (Fig.…”

Estrogen-Related Receptor α: A Significant Regulator and Promising Target in Bone Homeostasis and Bone Metastasis

“…Andrographolide, another natural compound targeted on ERRα from virtual docking screening, had been proven to suppress the formation of ERRα/PGC-1β complex and further reduce glutaminase metabolism during osteoclast differentiation. Inhibition on this regulatory axis attenuated osteoclasts-mediated bone resorption and bone loss in vivo [30]. Taken together, these data illustrated that ERRα functioned as a promoting effector to facilitate osteoclast differentiation and bone absorption involving various mechanism networks (Figure 2), targeting on the receptor would be a promising strategy for degenerative bone disorders.…”

“…An alternative probability is that the functional performance of ERRα is tightly dependent on the specific cellular environment and post-translational modifications (PTMs) [27,29]. In addition, many specific inhibitors or natural products that function as agonists or antagonists of ERRα were identified, and these compounds have been implicated in the treatment of cancers or metabolism-disorder diseases [12,30]. Therefore, it is essential to explore the defined role of ERRα in a certain tumor model and achieve the precise therapy using the specific pharmacochemistry targeting on ERRα.…”